IPTG (isopropylthiogalactoside) is commonly used to induce protein expression in Lac operon-regulated gene in E. Coli, because IPTG O a. is a repressor to Lac operon. O b. is an enhancer binding compound. O c. O d. unwinds DNA, leading to DNA duplication and transcription. is a mimetic of allolactose, that binds to repressor, causing it release from the operator of the lac operon, leading to transcription.

IPTG (isopropylthiogalactoside) is commonly used to induce protein expression in Lac operon-regulated gene in E. Coli, because IPTG O a. is a repressor to Lac operon. O b. is an enhancer binding compound. O c. O d. unwinds DNA, leading to DNA duplication and transcription. is a mimetic of allolactose, that binds to repressor, causing it release from the operator of the lac operon, leading to transcription.

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter14: Gene Regulation

Section: Chapter Questions

Problem 13TYU: INTERPRET DATA Develop a simple hypothesis that would explain the behavior of each of the following...

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. Partial diploid forms of E. coli were created, each of which contained a com- plete lactose operon at its normal chromosomal site and the regulatory se- quences only (laci, P laco) on a plasmid. Predict the effect of each mutation on the activity of B-galactosidase before and after the addition of inducer. Use -, +, or ++ to indicate approximate activity levels. Briefly explain the basis for each of your predictions.
Describe the binding of RNA polymerase, repressors, andactivators to the lac operon when both lactose and glucose are scarce. What is the effect of these scarcities ontranscription of the lac operon?
V The trp repressor binds to the operator region of DNA as a dimer (two repressor protein subunits bound together as a unit). You isolate a new mutant e, coli strain that you call Rnovel. In this strain, the repressor protein cannot attach to DNA (it cannot bind to the operator) but it can make dimers. In this strain, how is expression of the trp operon regulated? OA. inducible OB. noninducible OC. constitutive OD. repressible Reset Selection 3 E D Q 4 R F % 5 T MacBook Pro G < C 6 Y 7 H C 00 * 8 → 9 K 0 O P +
Consider the lac operon of E. coli. Specifically, explain the following: a. Describe the overall chromosomal structure/organization of the operon, indicating the location and function of the regulatory regions and the structural genes. b. Is lac a catabolic or anabolic pathway? Explain. Is the operon inducible or repressible? Explain. c. Describe the mechanisms involved in negative control & positive control
. For each of the following growth conditions, whatproteins would be bound to lac operon DNA? (Listthe proteins, but do not include RNA polymerase.)a. glucoseb. glucose + lactosec. lactose
Indicate whether each of the following statements about the lac operon are true or false: Bacteria with a lac phenotype are unable to use lactose because of some defect in expressing the genes A constitutive Lac+ phenotype could mean either that the production of repressor is defective or that the operator sequence is defective The lacl gene is next to, but is not part of, the lac 1. TRUE operon 2. FALSE Bacteria with a lac* phenotype cannot grow on media containing lactose as the only sugar The structural genes of the lac operon are each transcribed as a separate MRNA Expression of the Lac Repressor from the lacl promoter is regulated by lactose
. In the lac operon of E. coli, if glucose levels increase while lactose levels decrease, what will happen in the regulation of genes controlling the enzymes needed to catabolize lactose? the lac operon will be activated due to cAMP-assisted CAP binding to a site near the promoter the lac operon will be activated due to CAP detachment from a site near the promoter the lac operon will be repressed due to cAMP-assisted CAP binding to a site near the promoter the lac operon will be repressed due to CAP detachment from a site near the promoter all of the above
The figure at the beginning of this chapter showsthe binding of both a Lac repressor tetramer and aCRP-cAMP complex to the regulatory region of thelac operon.a. What is the key feature of a regulatory protein suchas the Lac repressor or CRP that allows it to regulate specifically the genes or operons it is supposedto control?b. On the figure, show the positions of the followingcomponents: (i) A Lac repressor monomer; (ii) a Lacrepressor dimer; (iii) all four DNA binding domains ofthe Lac repressor tetramer; (iv) a single helix-turnhelix motif; (v) the o1 part and either the o2 or o3 partsof the lac operator (assume the operon would be transcribed from right to left on the figure); (vi) themultimerization domains of the four Lac repressormonomers; (vii) an inducer-interacting domain; (viii)the CRP-cAMP complex; and (ix) a DNA loop.c. What is the physical basis for the formation of theDNA loop shown in the figure?d. On the figure, show the position of two axes ofsymmetry in the sequence…
. Mutants were isolated in which the constitutive phenotype of a missense lacI mutation was suppressed.That is, the operon was now inducible. These suppressor mutations mapped to the operon, not to the lacIgene. What could these mutations be?
The molecules indicated below can be used experimentally due to their roles in relation to the expression of the lac operon. Drag the listed molecules to their corresponding bin. Reset Help ONPG IPTG X-Gal allolactose Dragable beta-galactosidase cleaves this molecule to form a visible yellow product. beta-galactosidase cleaves this molecule which then dimerizes to form a visible blue product. This molecule induces the transcription of the lac operon by inactivating the lac repressor.
If lactose isn't present in the environment of an E. coli, what is the state of the lac operon? O a. It is "on" (high transcription) because will glucose will still be present, so the operon's products will be needed. O b. It is "on" (high transcription) because CAP will be bound to the promoter O c. It is "off" (no transcription) because RNA polymerase will be inactivated d. It is "off" (no transcription) and the repressor will be bound to the operator
Answer this 3 part question: (MC) What is the function of lactose in regulation of the lac operon? 1. activates a repressor protein 2. activates an activator protein 3. inactivates a repressor protein 4. inactivates an activator protein Consider a bacterial strain with a lac operon Р. О Y A a) Mention which parts of the DNA region shown in the diagram encode for • Enzyme proteins? • Operator • Promoter • Repressor gene b) Where would the lac repressor be bound in a E. coli cell that is growing in ( • high lactose? No lactose